Puzzling signals seen by LIGO may be gravitational wave split in two

We normally see the effects of gravitational lensing when it bends light

SXS, the Simulating eXtreme Spacetimes (SXS) project

Early in the morning on 28 August, the Laser Interferometer Gravitational Wave Observatory (LIGO) felt two ripples in spacetime wash over it. But due to a strange effect of general relativity, the two signals may actually be from the same event.

Gravitational waves, which stretch and contract spacetime itself, emanate from massive objects moving around and colliding with each other. LIGO detected its first gravitational wave from a pair of black holes merging in 2015, and since then has observed more …